COMPARISON OF THE CARDIOPROTECTIVE EFFICACY OF SUPEROXIDE-DISMUTASE IN A SINGLE AND A REPETITIVE CORONARY-OCCLUSION MODEL IN RABBIT HEARTS

The effects of exogenous superoxide dismutase (SOD) on acute myocardia l ischemia (MI) was investigated in isolated electrically-driven rabbi t hearts (Langendorff; constant pressure: 70 cm H2O, Tyrode solution, Ca++ 1.8 mmol/l, 37 degrees C). Acute regional ischemia (MI) was induc ed by occlusion of a coronary artery branch (CAO) and quantitated from epical dial NADH-fluorescence photography. SOD (48 U/ml) was applied either 30 min after CAO in a single coronary occlusion model (treatmen t) 30 min before the 2nd CAO in a repetitive coronary occlusion model (pre-treatment). SOD had no significant influence on the left ventricu lar pressure or the global coronary flow (p > 0.05). MI was significan tly diminished in hearts pre-treated with SOD before CAO (-25%) (p < 0 .05), but remained unaffected when SOD was applied after CAO (p > 0.05 ). The results suggest that superoxide anion radicals contribute to is chemic tissue injury. SOD shows cardioprotective proper-ties only if p resent in the ischemic rone, requiring the application of SOD before C AO in poorly collateralised rabbit hearts.